Wastewater treatment

ABSTRACT

Wastewater is treated on at least one apparatus positioned at a location on the surface of a body of seawater wherein a wastewater intake system takes in wastewater into the apparatus, the wastewater is treated on the apparatus to yield treated wastewater and sludge, and the treated wastewater and/or sludge is diluted with seawater prior to being discharged into the body of seawater. The wastewater treatment systems and methods can also be combined with desalination and/or power generation. In combination with desalination, the concentrate produced from the desalination process is mixed with treated wastewater or sludge prior to discharge to bring the resulting mixture to a salt concentration closer to the body of seawater than the unmixed concentrate, treated wastewater, or sludge. Combustible gases produced by the wastewater treatment process can be used to fuel a power generation system that can be used to produce electrical power for use by systems on the apparatus or transferred off the apparatus for other uses.

CROSS-REFERENCE OF RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/114,721, filed Apr. 25, 2005 which claims the priority ofU.S. provisional patent application Ser. No. 60/594,921 filed Apr. 23,2004. The priority of both prior applications is claimed.

FIELD OF THE INVENTION

The invention relates to systems and methods for treating wastewater(WW) using an apparatus positioned offshore.

BACKGROUND

Most municipalities presently employ land-based WW treatment facilitiesdownstream of their sewage collection systems to process raw WW into amore innocuous form. The end products of conventional WW treatmentsystems are treated WW and sludge. Depending on its level of treatmentand resultant quality, the treated WW can reused or disposed of in abody of seawater (SW) adjacent to the WW treatment plant. Sludge istypically dumped at an offsite location, but is sometimes processed foruse as fertilizer. The creation and disposal of these end products aswell as the general operation of a WW treatment plant can haveundesirable effects. For example, land-based WW treatment plants oftenoccupy expensive waterfront real estate, present an eyesore to thesurrounding community, and emit unpleasant odors. Worse, the cumulativedischarge charge of end products created by the WW treatment process candamage the environment.

SUMMARY

The invention is based on the development of environmentally friendlysystems and methods of processing large volumes of untreated WW (e.g.,raw sewage from a municipal sewer system) into treated WW and sludge endproducts. By positioning one or more components of the WW operationoffshore, the need for expensive shore-side land is reduced and anyunpleasant odors are minimized. The invention also provides severalinnovations to reduce the impact of WW treatment on the marineenvironment including the pre-dilution of one or more WW treatment endproducts prior to discharge into a body of SW, plankton avoidanceequipment, and having intake and discharge at different depths. Thediluent in the pre-dilution step can be water from the body of SW orconcentrate produced from a desalination operation (e.g., such that theresulting mixture has a salt concentration close to that of the body ofSW). The WW treatment systems and methods of the invention can be usedin combination with desalination and power generation components.

Accordingly, the invention features a method of treating wastewater onat least one apparatus positioned at a location on the surface of a bodyof seawater. This method includes the steps of intaking wastewater intothe at least one apparatus; treating the wastewater taken into the atleast one apparatus to yield end products including treated wastewaterand sludge; diluting at least one of the end products with seawater toyield an at least one diluted end product; and discharging the at leastone diluted end product into the body of seawater. The at least one ofthe end products can include treated wastewater or sludge. The step ofdiluting the at least one of the end products with seawater occurs onthe apparatus, for example. The at least one diluted end product canhave a salinity level substantially equal to the salinity level of theseawater at the area where the at least one diluted end product isdischarged. The at least one diluted end product can have a temperaturesubstantially equal to the temperature of the seawater at the area wherethe at least one diluted end product is discharged. The at least onediluted end product can have a salinity level and temperaturesubstantially equal to the salinity level and temperature of the body ofseawater at the area where the at least one diluted end product isdischarged. The step of diluting the at least one end product withseawater can be performed in a mixing tank including a space in whichthe at least one end product can be mixed with seawater to form the atleast one diluted end product, an inlet for introducing the at least oneend product into the space, an inlet for introducing seawater into thespace, and an outlet for discharging the at least one diluted endproduct from the space, the outlet being in fluid communication with adischarge port.

In the method, at least about 75 million liters of wastewater aretreated per day. The method can further include transferring wastewaterto be treated from a land-based site to the apparatus and transferringone of the end products (e.g., treated wastewater, sludge) from theapparatus to land. The at least one apparatus includes a singlesea-going vessel or a platform. The at least one apparatus can alsoinclude at least two devices in fluid communication (e.g., sea-goingvessel and a platform). The wastewater taken into the at least oneapparatus can be raw sewage, e.g., raw sewage that has been subjected toa step to remove from the wastewater undissolved solids and/orundissolved liquids. The step of treating the wastewater taken into theat least one apparatus to yield the end products can include removingconstituents of the wastewater by a sedimentation step and a membranefiltration step. The at least one apparatus can include a nuisancereduction system for reducing at least one of sound or odor emission.

Treating the wastewater taken into the at least one apparatus to yieldend products including treated wastewater and sludge can further yieldat least one combustible gas. The method can further include the step ofcapturing the at least one combustible gas, e.g., methane, andconverting it into electricity. The at least one apparatus can includean electricity producing means, e.g., a gas turbine-powered generator,for converting the at least one combustible gas into electricity. Theelectricity can power one or more of the following steps: intakingwastewater into the at least one apparatus, treating the wastewatertaken into the at least one apparatus to yield end products includingtreated wastewater and sludge, diluting at least one of the end productswith seawater to yield an at least one diluted end product, anddischarging the at least one diluted end product into the body ofseawater. The at least one apparatus can further include a means fortransferring the electricity from the at least one apparatus to aland-based distribution system. In the method, at least a first portionof the electricity can be transferred to the land-based distributionsystem, and at least a second portion of the electricity can power oneor more of the following steps: intaking wastewater into the at leastone apparatus, treating the wastewater taken into the at least oneapparatus to yield end products including treated wastewater and sludge,diluting at least one of the end products with seawater to yield an atleast one diluted end product, and discharging the at least one dilutedend product into the body of seawater.

Another method performed on at least one apparatus positioned at alocation on the surface of a body of seawater within the inventionincludes the steps of: intaking wastewater and seawater into the atleast one apparatus; treating the wastewater taken into the at least oneapparatus to yield end products including treated wastewater and sludge;desalinating the seawater on the at least one apparatus to yielddesalinated water and a concentrate; mixing the treated wastewater withthe concentrate to make a treated wastewater-concentrate mixture; anddischarging the treated wastewater-concentrate mixture into the body ofseawater. The treated wastewater-concentrate mixture can have a salinitylevel substantially equal to the salinity level of the seawater at thearea where the treated wastewater-concentrate mixture is discharged. Thetreated wastewater-concentrate mixture can have a temperaturesubstantially equal to the temperature of the seawater at the area wherethe treated wastewater-concentrate mixture is discharged. The treatedwastewater-concentrate mixture can have a salinity level and temperaturesubstantially equal to the salinity level and temperature of the body ofseawater at the area where the treated wastewater-concentrate mixture isdischarged.

The at least one apparatus can include at least a first device such as asea-going vessel and a platform and a second device such as a sea-goingvessel and a platform. In this method, the first and second devices canbe in fluid communication. The step of treating the wastewater takeninto the at least one apparatus to yield end products including treatedwastewater and sludge can be performed on the first device and the stepof desalinating the seawater can be performed on the second device. Thestep of mixing the treated wastewater with the concentrate to make atreated wastewater-concentrate mixture can be performed in a mixing tankincluding a space in which the treated wastewater and concentrate can bemixed, an inlet for introducing the treated wastewater into the space,an inlet for introducing the concentrate into the space, and an outletfor discharging the treated wastewater-concentrate mixture from thespace, the outlet being in fluid communication with a discharge port.Treating the wastewater taken into the at least one apparatus to yieldend products including treated wastewater and sludge can further yieldat least one combustible gas, e.g., methane.

The method can further include the step of capturing the at least onecombustible gas and converting it into electricity. In this method, theat least one apparatus can include an electricity producing means, a gasturbine-powered generator, for converting the at least one combustiblegas into electricity. The electricity can power one or more of thefollowing steps: intaking wastewater into the at least one apparatus,treating the wastewater taken into the at least one apparatus to yieldend products including treated wastewater and sludge, diluting at leastone of the end products with seawater to yield an at least one dilutedend product, and discharging the at least one diluted end product intothe body of seawater. The at least one apparatus can further include ameans for transferring the electricity from the at least one apparatusto a land-based distribution system. In this method, at least a firstportion of the electricity can be transferred to the land-baseddistribution system, and at least a second portion of the electricitycan power one or more of the following steps: intaking wastewater intothe at least one apparatus, treating the wastewater taken into the atleast one apparatus to yield end products including treated wastewaterand sludge, diluting at least one of the end products with seawater toyield an at least one diluted end product, and discharging the at leastone diluted end product into the body of seawater.

In another aspect, the invention features a system for treatingwastewater on at least one apparatus positioned at a location on thesurface of a body of seawater. This system includes: at least oneapparatus being positioned at a location on the surface of a body ofseawater; a wastewater treatment system installed on the at least oneapparatus, the wastewater treatment system capable of removing organicmaterial from wastewater to yield end products including treatedwastewater and a sludge; a seawater intake system installed on the atleast one apparatus and including a device for taking up seawater fromthe body of seawater; a mixing system for mixing at least one of the endproducts with seawater to yield an at least one diluted end product, themixing system being installed on the at least one apparatus incommunication with the wastewater treatment system and including a spacein which the at least one of the end products can be mixed with seawaterto form the at least one diluted end product, an inlet for introducingthe at least one of the end products into the space, an inlet forintroducing seawater into the space, and an outlet for discharging theat least one diluted end product from the space; and a discharge systemfor discharging the at least one diluted end product from the at leastone apparatus, the discharge system being installed on the at least oneapparatus and including at least one discharge port. The wastewatertreatment system is capable of processing at least about 75 millionliters of wastewater per day. The system can further include aland-based site, e.g., a sewage collection facility, in fluidcommunication with the at least one apparatus. The device for taking upseawater can include at least one water intake positioned in the body ofseawater at a first depth. The at least one discharge port can bepositioned at a site not at the first depth, e.g., the at least onedischarge port can be positioned at a site deeper than the first depthor at a site more shallow than the first depth. The at least onedischarge port can be positioned in or below a thermocline and the firstdepth can be above the thermocline. The at least one discharge port canbe positioned above a thermocline and the first depth can be in or belowthe thermocline. The water intake can be movable such that the waterintake system can intake water from various depths to reduce the intakeof plankton. The apparatus can include instrumentation and sensors fordetecting the presence of and depth of thermoclines in the body ofseawater, and instrumentation and sensors for detecting the presence ofand depth of plankton in the body of seawater.

In the system, the wastewater treatment system capable of removingorganic material from wastewater to yield end products including treatedwastewater and a sludge is further capable of yielding at least onecombustible gas, e.g., methane. The system can further include at leastone energy producing means, e.g., a gas turbine-powered generator,installed on the at least one apparatus for converting the at least onecombustible gas into electricity. The electricity can power one or moreof the following: the at least one apparatus, the wastewater treatmentsystem, the seawater intake system, the mixing system, and the dischargesystem. The system can further include a means for transferring theelectricity from the at least one apparatus to a land-based distributionsystem. At least a first portion of the electricity can be transferredto the land-based distribution system, and at least a second portion ofthe electricity can power one or more of the following: the at least oneapparatus, the wastewater treatment system, the seawater intake system,the mixing system, and the discharge system.

Also within the invention is a method of treating wastewater on at leastone apparatus positioned at a location on the surface of a body ofseawater. This method includes the steps of intaking wastewater from aland-based site into the at least one apparatus; treating the wastewatertaken into the at least one apparatus to yield end products includingtreated wastewater and a sludge, and transferring the treated wastewaterand the sludge to land, wherein none of the wastewater, the treatedwastewater, or the sludge is discharged into the body of seawater. Inthis method, the treated wastewater can be potable.

Unless otherwise defined, all technical terms used herein have the samemeaning as commonly understood by one of ordinary skill in the art towhich this invention belongs.

By the phrase “treated WW” is meant WW that has been subjected to atleast one WW treatment step.

As used herein, the terms “land-based,” “on land,” “shore-based,” and“on shore” refer to systems and structures that are primarily orentirely disposed on land or shore.

By “offshore” systems or apparatuses is meant those that are primarilyor entirely disposed in or on the surface of a body of SW such as anocean, lake, river, bay, or sea.

As used herein, the term “thermocline” refers to a temperature gradientin a layer of sea water, in which the temperature decrease with depth isgreater than that of the overlying and underlying water.

The terms “seawater” or “SW” are used in the broad sense to encompasswater from any large body of SW such as an ocean, lake, river, bay, orsea regardless of whether the water is salt water, fresh water, orbrackish water. Similarly, “body of seawater” or “body of SW” includeoceans, lakes, rivers, bays, or seas regardless of whether the body ofSW is salt water, fresh water, or brackish water As used herein, theterm “substantially equal” does not refer to a comparison ofquantitative measurements, but rather that the impact on the affectedmarine life or ecosystem is qualitatively negligible.

Although apparatuses, methods and materials similar or equivalent tothose described herein can be used in the practice or testing of thepresent invention, suitable apparatuses, methods and materials aredescribed below. All publications, patent applications, patents, andother references mentioned herein are incorporated by reference in theirentirety. In the case of conflict, the present specification, includingdefinitions will control. In addition, the particular embodimentsdiscussed below are illustrative only and not intended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an apparatus for treating WW.

FIG. 2 is a schematic view of an apparatus for treating WW and atransfer vessel.

FIG. 3 is a side view of an apparatus for treating WW and desalinatingSW.

FIG. 4 is a side view of an apparatus for treating WW and desalinatingSW, the apparatus including an energy producing means for convertingcombustible gases into electricity.

FIG. 5 is schematic view of three apparatuses of a system fluidlyconnected to one another.

DETAILED DESCRIPTION

The invention encompasses WW treatment methods and systems forprocessing a large volume of WW such as at least about 75 million liters(e.g., greater than about 50 million, 100 million; 200 million, 300million, 400 million, 500 million, or 600 million or more) of WW perday. The methods and systems of the invention utilize an apparatus (orthe combination of 2, 3, 4, 5, 6, 7, 8, 9, 10 or more apparatuses)positioned on the surface of a body of SW. Any suitable apparatuspositionable on the surface of a body of SW and capable of housing a WWtreatment system might be used. The apparatus can be self-propelled,non-self propelled, manned, or unmanned, but is preferably a sea-goingvessel because of mobility and ease of construction (i.e., the vesselcan be built at any suitable shipyard in an industrialized country andmoved from the shipyard to the place of use). Examples of a suitablesea-going vessel include a barge; a floating platform secured to thefloor of the body of SW; a bulk carrier vessel (e.g., single or doublehull bulk carrier vessels); a sea-going vessel designed to transportcargo such as petroleum, grain, or iron ore that has been retrofittedfor housing the components and systems for treating WW described herein;and a newly constructed, sea-going vessel specifically designed forhousing the components and systems for treating WW described herein.

An appropriate sea-going vessel for use in the invention is a single- ordouble-hull vessel that has, e.g., a dead weight tonnage (dwt) ofbetween about 10,000 to 500,000; 30,000 and 50,000; 65,000 and 80,000;about 120,000; about 250,000 and 300,000; or more than 300,000. Thepreferred dwt will depend on the particular design of a given system(e.g., the volume of WW to be treated per period of time), but should besufficient to maintain the minimum draft required to keep the vesselafloat, and/or match the desired treatment capacity of the system on thevessel. As described herein, an apparatus can be moored or anchored tothe floor of the body of SW or to a structure such as a dock. Toaccommodate any new or emerging technologies for treating WW, theapparatus is preferably arranged to accept modular upgrades, i.e.,various components can be replaced/upgraded separately apart from othercomponents.

Various functional components can be installed on the apparatusincluding WW treatment components capable of removing organic materialfrom WW to yield end products including treated WW and sludge; a SWintake system including a device for taking up SW from the body of SW; amixing system for mixing sludge and/or treated WW with SW to yield adiluted end product; and a discharge system including a discharge portfor discharging the at least one diluted end product from the apparatus.

The WW treatment system generally includes a land-based site such as asewage collection facility that collects WW from residential(household), commercial, industrial, government, and/or agriculturalsources. WW from the land-based site is transferred to the apparatus fortreatment, e.g., by a pipeline or shuttle ship. The WW treatment systemcan include one or more (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) WWtreatment components specifically selected to handle the composition ofWW from a particular source. WW treatment components suitable for use inthe invention are any capable of performing at least one step in a WWtreatment protocol, e.g., removing one or more non-water substances suchas solids, oils, waxes, organic matter, and dissolved solids from theWW. Treatments and devices used in land-based WW treatment are wellknown in the art. See, e.g., Wastewater Treatment Plants: Planning,Design, and Operation, Second Edition, Syed R. Qasim, Ed., CRC Press,1998; and Design of Municipal Wastewater Treatment Plants (Asce Manualand Reports on Engineering Practice), 4th edition, American Society ofCivil Engineers, 1998. These and other components can be used in thesystems, apparatuses, and methods described herein with slight or nomodifications. Any combination of WW treatments, systems, or methodssuitable for treating WW can be used on an apparatus as describedherein.

In some embodiments, WW treatment is performed on a single apparatushaving thereon all WW treatment components required to sufficientlytreat the WW for its intended purpose. In other embodiments, however,the WW treatment steps are performed on at least two (e.g., 3, 4, 5, 6,7, 8, 9, 10 or more) apparatuses each having at least one (e.g., 2, 3,4, 5 or more) different WW treatment. For example, a first apparatus caninclude preliminary WW treatment steps such as course screening and gritremoval, and a second apparatus can include WW treatment steps such asmembrane-based WW treatments (e.g., cloth media filtration, reverseosmosis). In the latter example, the WW treated on the first apparatusis transported (e.g., by a pipeline or shuttle ship) to the secondapparatus for additional treatment.

In the invention, WW might also be subjected to one or more preliminarytreatments on land before being transferred to an apparatus for furthertreatment. Preliminary treatments can include removing large objects orimpurities such as sticks, rags, large food particles, sand, and gravelfrom WW. A series of grates, screens, or like devices can be used forpreliminary treatment. As the WW passes through the grates/screens, thelarge objects/impurities are caught, while the remainder of the WW flowsthrough for possible further processing. Another example of apreliminary treatment device is a grit chamber where sand, gravel, andother rock-like materials are removed.

In a typical system, after the WW has been subjected to one or morepreliminary treatments on land, it is transferred to the apparatuspositioned in the body of SW where it is directed to one or moreadditional WW treatments. For example, a WW treatment step that oftenfollows preliminary treatment involves a clarification/settling tankwhere the solids are settled out (often referred to as primarytreatment) and digested by microorganisms in the presence of oxygen(aerobic digestion) or in the absence of oxygen (anaerobic digestion).In some embodiments, the clarification tank is a component of asequencing batch reactor or bioreactor which provides for the settlingof solids, as well as microorganism-mediated removal of organic matterfrom the WW (e.g., Sequencing Batch Reactors such as the AquaMB Process™marketed by Aqua-Aerobic Systems, Inc., Rockford, Ill., and ZeeWeed®membrane bioreactor marketed by Zenon, Oakville, Ontario, Canada;anaerobic digestion systems marketed by US Filter, Warrendale, Pa.).Although any suitable microorganism-mediated treatment of WW can be usedin systems, apparatuses and methods described herein, anaerobicdigestion systems may be preferred over aerobic digestion systemsbecause they generally have reduced operating horsepower requirements,do not require aeration, and yield less sludge.

After the WW is subjected to one or more clarification/settling tanks,the WW can then be subjected to a membrane-based treatment such as clothmedia filtration, in which bulk solids are separated from the WW stream.An example of a cloth media filter that may be used in systems of theinvention is the AquaDisk® filter marketed by Aqua-Aerobic Systems, Inc.(Rockford, Ill.). In a typical system of the invention, a plurality ofAquaDisk® filters are housed within a steel (or other metal) tank orbasin, one disk in front of another. WW may be further treated byfiltration (e.g. using a series of filters having decreasing pore sizesthat are capable of removing particles having a diameter greater than 1,0.1, 0.01, or 0.001 microns; using microfiltration and/orultrafiltration membranes) any membrane-based filtration that removessolids), reverse osmosis, chlorination, UV irradiation, mineralization,pH balancing, evaporation vapor compression, electrodialysis, multipleeffect distillation, electrodionisation or other methods (i.e.,polishing, tertiary, quaternary, or advanced treatment). In applicationswhere chlorinated treated WW is to be discharged into a body of SW, achlorine-neutralizing chemical can be added to prior to discharge.

Other WW treatment processes that might be used in the invention are anyphysical, chemical, or biological means to improve the quality of thetreated WW. For example, chemicals can be added to the treated WW tohelp settle out or strip out nutrients such as nitrogen, phosphorousmight be removed from treated WW using a coagulant, and ammonia might beremoved by air stripping. Granular media filtration might be used toremove suspended solids that have not been removed through othertreatment processes. Granular activated carbon can be used to removeorganic compounds. Ion exchange resins can be used to remove someorganics or other materials. Cavitation generated by ultrasound as wellas hydrodynamic cavitation can be used to treat WW.

In place of or in addition to reverse osmosis, however, WW can bepurified by a variety of other treatment processes includingnanofiltration, molecular sieves, and ultrasonic treatment.Nanofiltration techniques are used for removing dissolved organics andinorganics, have been used in water purification and reuse applications(see, e.g., Holt et al., Science 312:1003-1004, 2006; U.S. Pat. No.6,787,037), and nanofiltration membranes are commercially available(e.g., NTR 729HF membrane marketed by Nitto Denko Corp, Japan). The useof molecular sieves in industrial applications such as WW treatment iswell known, see e.g., D. M. Ruthven in Principles of Adsorption andAdsorption Processes, John Wiley and Sons, New York, 1984; Phase IIBTopical Report, U.S. Department of Energy, National Energy TechnologyLaboratory, Pittsburgh, Pa., “Surface-altered zeolites as permeablebarriers for in situ treatment of contaminated groundwater,” 2002;Environ. Sci. Technol. 33:4326-4330, 1999; and U.S. Pat. No. 6,863,826.Molecular sieves are commercially available from a number of companies,including, e.g., ZeoponiX, Inc. (Boulder, Colo.).

To minimize harm to the marine environment caused by discharge of a WWtreatment end product, the WW treatment apparatus can include a SWintake system for taking up SW from the body of SW on which theapparatus is positioned, a mixing system for mixing at least one of theend products (sludge and/or treated WW) with SW to yield an at least onediluted end product, and a discharge system for discharging the at leastone diluted end product. Any suitable device for taking up SW from abody of SW might be used for the SW intake system. In general, the SWintake system includes an intake port positionable in the body of SW, aconduit for transferring SW from the intake port to the mixing system,and one or more pumps and/or valves for intaking the SW and directing itto the mixing system. In an embodiment in which the apparatus is asea-going vessel, the SW intake can include a pipe that extends from thehull of the vessel into the body of SW. In other embodiments, the SWintake of the SW intake system can include one or more apertures (e.g.,one or more sea chests) in the hull of the vessel below the water line.

In those embodiments where treated WW is being diluted and thendischarged into the body of SW on the surface of which the apparatus ispositioned, the SW intake can be positioned in the body of SW at a depthdifferent than the depth at which the diluted, treated WW is dischargedso that the treated WW that has been diluted and discharged is not takenup by the SW intake. Preferably the intake depth and discharge depth areseparated by a thermocline to further reduce intake of discharge.

Systems for treating WW as described herein can be operable to intake SWinto the SW intake system at various depths to reduce intake ofplankton. For example, if the apparatus is a sea-going vessel having adwt of over 100,000, the draught is usually at least 10 meters. On sucha sea-going vessel, a sea chest located on the lower most region of thehull on the vessel can intake SW below 10 meters to reduce planktonintake. In another embodiment, the SW intake can be movable so that itcan be placed at a depth which minimizes the intake of plankton. In someembodiments, the system for treating WW including the sea-going vesselis operable to allow an operator of the sea-going vessel to choosebetween using a sea chest or a SW intake member to intake SW into themixing system. An operator may choose to use a sea chest or a SW intakemember to intake SW based upon the location and depth of thermoclines inSW surrounding the vessel and/or based on the amount of plankton at anyparticular depth. To assist in plankton/thermocline detection, the WWtreatment apparatus of the invention can be equipped withinstrumentation and sensors to allow the operator to detect the presenceof and depth of thermoclines and/or plankton populations in thesurrounding body of SW. The mixing system on the apparatus of theinvention can take the form of any suitable device capable of mixing atleast one of the end products (treated WW, sludge) with SW from the bodyof SW on which the WW treatment apparatus is positioned. Such a systemis operable to dilute and/or change the temperature of the end productbefore returning it to the body of SW. Preferably, the diluted endproduct has a salinity level and/or temperature equal to orsubstantially equal to that of the SW at the area where it isdischarged. For example, the salinity of the diluted end product isbetween about 150-50% (e.g., 151, 140, 130, 120, 110, 100, 90, 80, 70,60, 50, 49%) of the seawater at the area where the diluted end productis discharged, and the temperature of the diluted end product is betweenabout 20° C. greater (e.g., 22° C., 20° C., 18° C., 16° C., 14° C., 12°C., 10° C., 8° C., 6° C., 4° C., 2° C., 1° C. greater) and 20° C. lessthan (e.g., 22° C., 20° C., 18° C., 16° C., 14° C., 12° C., 10° C., 8°C., 6° C., 4° C., 2° C., 1° C. less than) the temperature of theseawater at the area where the diluted end product is discharged.

The mixing system can include a mixing tank having a chamber or space inwhich a WW treatment end product is mixed with SW from the body of SW toform a diluted end product, an inlet for introducing the at least oneend product into the space, an inlet for introducing SW from the body ofSW into the space, and an outlet for discharging the diluted end productfrom the space. The space or chamber of the mixing tank can include adevice for enhancing the mixing of end product with SW from the body ofSW. As an example, a series of baffles and a mixing barrier having aplurality of apertures might be included in the space. The size, shape,location and number of apertures are selected to optimize mixing of theend product with the SW from the body of SW. The apertures induceturbulence in fluids flowing through the mixing barrier. The mixingbarrier extends from one side of the mixture tank to the opposing sideof the mixing tank. Adjacent baffles are coupled to opposing sides ofthe mixing tank. The baffles are arranged in a staggered relationshipsuch that a portion of each baffle overlaps with an adjacent baffle. Thefluid passing though the mixing barrier must follow a convoluted routebefore reaching the discharge system for discharging the at least onediluted end product from the apparatus. Other devices for enhancingmixing that may be used in the space include high speed paddle mixersand static mixers.

The WW treatment system on the apparatus might also include otherdevices for regulating the temperature of an end product to bedischarged, e.g., to change the temperature of an end product so that itis the same as or substantially equal to the temperature of the SW atthe area where it is discharged. As an example, the device might takethe form of a heat exchange system including a heat exchanger and acooling system.

After treatment and/or dilution, an end product is discharged from theapparatus via a discharge system. The discharge system can take the formof any suitable device capable of transferring the end product from theapparatus to the body of SW in which the apparatus is positioned.Typically, the discharge system includes at least one discharge portpositioned in or above the SW surrounding the apparatus. In embodimentswhere the apparatus is a sea-going vessel, one or more discharge portsare typically disposed in the hull of the vessel through which thediluted end product is discharged into the SW surrounding the vessel.The discharge port(s) may be disposed in the hull of the vessel suchthat the discharge port(s) is physically located below or above thewater line of the vessel. A plurality of discharge ports can be disposedat intervals along the vessel, allowing the discharge to be dischargedover a substantial portion of the vessel's length. A plurality ofdischarge ports may be mounted on dispersion devices that enable thedischarge ports to move in a full hemi-sphere range. The dispersiondevices may include a universal joint, a swivel, a gimble, a ball andsocket, or other similar devices known to one skilled in the art.Through the oscillation or motion of the plurality of discharge ports,the diluted end product should be more evenly dispersed into thesurrounding SW. The discharge system may further include a pump toincrease the water pressure of the diluted end product prior to beingdischarged through the discharge port(s).

The discharge system for discharging an end product can further includea member extending down from the hull of the vessel with a plurality ofdischarge ports disposed on the member. Depending on various factorssuch as water depth, water temperature, water currents, and thesurrounding ecosystem, the member may extend to the depth or depths thatoptimize the mixing of the diluted end product with the SW at the areawhere the at least one diluted end product is discharged. In such asystem, the member can be lowered from and retracted to the vessel bymechanical means, such as, for example, a hydraulic assembly.Alternatively, other suitable means can be used to lower and retract themember, including those used in conventional maritime drillingoperations. In another embodiment, the member can have sufficient massand/or density that the member can be lowered from the vessel to adesired depth without mechanical assistance. Such a member is generallyretracted to the vessel by mechanical means.

Because an apparatus as described herein may be positioned above or neara thermocline in some cases, discharge ports can be disposed within orbelow a thermocline region relative to the SW intake of the SW intakesystem. For example, wherein the discharge system includes a pluralityof discharge ports and the SW intake includes a SW intake member, themember extends into or below a thermocline region and the dischargeports are disposed above the thermocline region. As another example,wherein the SW intake of a SW intake system includes a sea chest, andthe discharge system includes a member having discharge ports disposedthereon, the discharge ports are located on the member such that eachdischarge port is disposed within or below a thermocline region relativeto the sea chest. Such a configuration may reduce or eliminate uptake ofdischarged end product(s) into the SW intake system.

In addition to treated WW, another end product of the WW treatmentprocess is sludge. In general, the sludge generated by the WW treatmentprocess is treated on the apparatus before either being diluted anddischarged from the apparatus into the body of SW or transferred toland. The apparatus can therefore include at least one (e.g., 1, 2, 3,4, 5 or more) sludge treatment component that processes the sludge. Asan example, the sludge component can include a digestion tank whereinaerobic and/or anaerobic digestion by bacteria is used to decomposeorganic components in the sludge. To kill disease-causing organisms, thesludge may also be treated with microbe killing agents such as causticchemicals or ultraviolet light. Ultrasound treatment might also be usedto decrease sludge quantity (volume and mass) and increase the biogasyield (which can be used as fuel to generate power as described below).See, e.g., Kulkarni et al., Resonance, December, p. 64-74, 2000; andU.S. Pat. Nos. 6,780,306, 5,611,993, 6,773,597, and 6,578,780.

The sludge resulting from WW treatment can be transferred to aland-based facility for further processing, disposal, or use (e.g., asagricultural fertilizer). For example, a tugboat drawn barge can be usedas a transfer vessel to transfer treated sludge from an apparatuspositioned in a body of SW to a land-based sludge disposal/distributionfacility. Alternatively, if the apparatus is located adjacent to a dock,the treated sludge can be transferred from the apparatus to a land-basedfacility via a conveyor belt disposed on the dock and/or a vehicle suchas a truck. To facilitate handling, the mass of sludge can be reduced bydewatering, e.g., using a belt filter press to remove water from sludgeand produce a non-liquid cake.

If the treated sludge is being discharged into the body of SW on thesurface of which the apparatus is positioned, it is preferably dilutedwith SW from the body of SW before being discharged. The sludge can bemixed with SW from the body of SW as described above for mixing an atleast one end product with SW from the body of SW on the surface ofwhich the apparatus is positioned and discharged into this body of SWvia the discharge system for discharging the at least one end productfrom the apparatus.

In addition to those features described above, apparatuses of theinvention might further include a number of other features. For example,an apparatus as described herein can include one or more noise, odor,and/or vibration reduction devices in communication with any movingmechanical device aboard the apparatus. Such mechanical devices include,but are not limited to, a power source, a high pressure pump, a transferpump, and a SW intake pump. The noise reduction devices may include anyisolation, suspension, or shock absorbers known to one skilled in theart. The noise reduction devices also include any noise abatementtechnique known to one skilled in the art. Noise reduction devicesonboard an offshore apparatus that is a sea-going vessel may include ahull made of composite material or machines with precision manufacturingsuch that the rattle associated with a mechanical device is reduced whenoperating. Noise reduction devices can reduce the vibrations or noisetransmitted through the hull of the sea-going vessel and thereby reduceany disturbance or interference with normal aquatic or marine life. Forexample, the noise reduction devices can reduce interference with theacoustic communication between whales. Further, the noise reductiondevices can reduce the hearing hazard to the crew of the vessel.Vibration reduction devices can also be included on an offshoreapparatus. For example, such devices can be used to dampen vibrationsassociated with the movement of fluids (e.g., WW, SW, treated water,desalinated water) through piping in the vessel such as encasement on apipe's exterior. The encasement of a pipe can reduce velocity noise inpiping generated by the movement of water.

The WW treatment components described above might be used in conjunctionwith other systems including those for desalinating water and producingpower. For example, the WW apparatus positioned on a body of SW mightalso include a desalination system for producing desalinated water and aconcentrate (brine). Suitable desalination methods and systems aredescribed in U.S. patent application Ser. No. 10/734,050 and U.S. Pat.No. 7,081,205. An advantage of combining SW desalination with WWtreatment is that the concentrate resulting from the desalinationprocess can be mixed with the treated WW resulting from the WW process(e.g., in a mixing tank on the apparatus) such that the resultingmixture has a salinity close to that of the body of SW in which theapparatus is positioned. Detrimental effects of separately dischargingtreated WW and concentrate on the marine environment are thus reduced.

The WW apparatus positioned on a body of SW might also include a powergeneration system for producing power that can be used to run othercomponents of the WW treatment system or for use by other sea-based orland-based power-using systems. Fuel for the power generation system canbe supplied to the apparatus by a pipeline or shuttle ship. Examples ofsuitable fuels include biofuels (e.g., fuels such as ethanol or methanolthat are produced at least in part from biomass such as plants, straw,or biomass waste streams); petroleum-based fuels such as diesel fuel,jet fuel, kerosene, and gasoline; gases such as propane or natural gas;liquefied coal products, etc. Additionally or alternatively, thecombustible gases produced in the WW treatment process can serve as fuelfor the power generation system. The apparatus can include a tank forstoring the fuel.

The power produced by the power generation system can be used to powerone or more functions of the apparatus (e.g., propulsion device, controlsystems, WW treatment components, desalination components, etc.), ortransferred to another sea-based or land-based site for use ordistribution. The transfer of power can be accomplished by any suitablemeans known in the art for transferring power. As an example, the powergeneration system can produce electrical power which is transferred toan electricity-using device or electricity storage device (e.g., abattery) by an electrical conductor (e.g., metal cable).

Although any suitable power producing means can be used in the systemsand methods described herein, gas turbines, or gas turbine generators,may be preferred. Numerous different gas turbines outfitted ormodifiable to produce electricity that are suitable for use in theinvention are known and commercially available. For example, GE(Atlanta, Ga.) markets a Frame 9FB engine as well as the LM2500 GasTurbine, Rolls Royce (Houston, Tex.) markets a 501 series gas turbine,Siemens (Siemens AG, Orlando, Fla.) markets an SGT-500 gas turbine, andCentrax (Newton Abbot, England) markets the 501 series (e.g., 501-KIB3,501-KB5, 501-KN5, 501-KH5, 501-KB7, and 501-KN7) of gas turbine-poweredgenerators.

EXAMPLES

FIGS. 1-5 illustrate examples of various representative embodiments ofthe invention. Each of the components of the described systems might besubstituted with any other component that is suitable for the functiondescribed. In addition, the various systems described might berearranged in any suitable fashion.

Example 1

Referring now to FIG. 1, a system 10 for treating WW includes asea-going vessel 15 positioned on the surface of a body of SW 20 and aWW intake pipeline 40. The vessel 15 includes a hull 30; WW treatmentcomponents 60 a, 60 b, 60 c, and 60 d; a treated WW conduit 64; a sludgetreatment component 70; sludge conduits 62, 66; a SW intake 80, a mixingtank 75, and a discharge port 90. The WW intake pipeline 40 is shown influid communication with an intake port 50 positioned on the bottom ofhull 30. In operation, WW from a land-based sewer facility istransferred to the vessel 15 via the WW intake pipeline 40 to intakeport 50. The WW is then directed to one or more of WW treatmentcomponents 60 a-60 d where it is subjected to one or more WW treatmentprocesses that result in the production of treated WW and sludge as endproducts.

Although the treated WW could be removed from the vessel 15 andtransferred to land for reuse, in the embodiment shown in FIG. 1,treated WW is discharged from the vessel 15 into the body of SW 20.After processing in the WW treatment components 60 a-60 d, the treatedWW is transferred through conduit 64 into the mixing tank 75 whichincludes a space in which the treated WW can be diluted with SW from thebody of SW 20, an inlet for introducing the treated WW into the space,an inlet for introducing SW from the body of SW 20 into the space, andan outlet for discharging the diluted treated WW. For taking up SW fromthe body of SW 20 into the mixing tank 75, the vessel 15 includes a SWintake 80 that fluidly connects the body of SW 20 to the mixing tank 75.In the embodiment shown in FIG. 1, the SW intake 80 is shown as a pipehaving an aperture on its distal end. After the treated WW is dilutedwith SW from the body of SW 20 in the mixing tank 75, the mixture isdischarged from the vessel 15 through the discharge port 90 which isshown in FIG. 1 as extending from the hull 30 into the body of SW 20.

Similarly to the handling of the treated WW, the sludge resulting fromthe WW treatment process is also diluted with SW prior to discharge intothe body of SW 20. The sludge produced after treatment in the WWtreatment components 60 a-60 d is transferred to the sludge treatmentcomponent 70 via the sludge conduit 62. In the sludge treatmentcomponent 70, the sludge undergoes at least one sludge treatment step(e.g., bacterial digestion, ultraviolet light, dewatering) to yieldtreated sludge. The treated sludge is then transferred to the mixingtank 75 via the sludge conduit 62 where it is diluted with SW and thendischarged into the body of SW 20 via discharge port 90 into the body ofSW 20.

In FIG. 1, a thermocline 25 is shown in the body of SW 20. The SW intake80 is positioned in the body of SW at a depth below the thermocline 25,while the discharge port 90 is positioned at a depth above thethermocline 25. In this configuration, the thermocline acts as a barrierthat separates the SW intake 80 from the discharge port 90 such that SWto be used for diluting a treated WW end product is taken up from waterbelow the thermocline 25 and the diluted treated end product isdischarged into water above the thermocline. This separation reduces theuptake of treated diluted WW end product by the SW intake 80 and therebyincreases the efficiency of the system 10.

Example 2

In another embodiment of the invention, referring now to FIG. 2, a WWtreatment system 110 includes a sea-going vessel 115 situated on thesurface of a body of SW 20 and having disposed thereon WW treatmentcomponents for processing WW into treated WW and sludge, a SW intake 80,and a discharge port 90; a WW intake pipeline 50 for transferring WWfrom a sewer system 132 located on a parcel of land 122 to the vessel115; a transfer vessel 195 for transferring sludge produced by the WWtreatment components from the vessel 115 to a land-based sludgecollection/distribution facility 142 that includes a dock 144 and asludge transport vehicle 146. As in the embodiment shown in FIG. 1, thesea-going vessel 115 includes components (e.g., a SW intake 80, adischarge port 190, and a mixing tank) for diluting the treated WWproduced by the WW treatment components prior to discharge into the bodyof SW 20.

In this embodiment, treated sludge is transferred to a land-based sitefor use (e.g., as fertilizer) or disposal, rather than being dischargedinto the body of SW 20. The produced sludge is transported from thesea-going vessel 115 to the dock 144 via the transfer vessel 195. Fromthe dock 144, the sludge is moved to the land-based sludgecollection/distribution facility 142 for storage and/or furtherprocessing. The sludge transport vehicle 146 can be used to transportthe sludge from the facility 142 to another destination.

Example 3

Referring now to FIG. 3, a WW treatment system 210 includes a sea-goingvessel 215 positioned on the surface of a body of SW 20 and a WW intakepipeline 240. The vessel 215 includes a hull 230; a WW treatment system,a desalination system, and a mixing system for mixing the concentrateproduced by the desalination system with the treated WW produced by theWW treatment system. Similar to the embodiment of FIG. 1, the WWtreatment system includes a wastewater intake port 250 for intaking WWonto the vessel 215 from a WW pipeline 240; WW treatment components 260a, 260 b, 260 c, and 260 d; a treated WW conduit 264 for transportingtreated WW away from the WW treatment components 260 a, 260 b, 260 c,and 260 d; a sludge treatment component 270; and a sludge transferconduit 266. The desalination system of the vessel 215 includes a SWintake 280, a desalination component 276, a desalinated water dischargeport 277; and a concentrate conduit 279. Both the WW treatment systemand the desalination system are in fluid communication with aconcentrate-treated WW mixing system that include a mixing tank 275 anda discharge port 290.

In operation, WW from a land-based sewer facility is transferred to thevessel 215 via the WW intake pipeline 240 to intake port 250. The WW isthen directed to one or more of WW treatment components 260 a-260 dwhere it is subjected to one or more WW treatment processes that resultin the production of treated WW and sludge as end products. The treatedWW is conveyed to the mixing tank 275 via treated WW conduit 264. Thesludge is transported to the sludge treatment component 270 for furtherprocessing and then to the sludge transfer conduit 266 where it may beoffloaded from the vessel 215.

In the desalination system, SW to be desalinated is taken up into thevessel 215 by the SW intake 280 and then transferred to the desalinationcomponent 276 where it is desalinated, yielding desalinated water andconcentrate as end products. The desalinated water is sent from thedesalination component 276 through the desalinated water discharge port277 into the desalinated water pipeline 278 where it can be transportedto a land-based desalinated water distribution center. The concentrateproduced by the desalination process is transferred from thedesalination system 276 to the mixing tank 275 via the concentrateconduit 279.

In the mixing tank 275, the concentrate produced from the desalinationprocess is mixed with the treated WW resulting from the WW treatmentprocess. This mixture is then discharged from the vessel 215 by thedischarge port 290 into the body of SW 20. By mixing appropriate amountsof concentrate and treated WW, the resulting mixture can have a saltconcentration equal to or substantially equal to that of the body of SW20 into which it is being discharged.

Example 4

Referring now to FIG. 4, a sea-going vessel 315 includes a WW treatmentsystem in combination with a desalination system and a power generationsystem capable of transferring power off the vessel 315. Similar to theembodiment of FIG. 3, the WW treatment system includes a wastewaterintake port 350 for intaking WW onto the vessel 315 from a WW pipeline340; WW treatment components 360 a, 360 b, 360 c, and 360 d; a treatedWW conduit 364 for transporting treated WW away from the WW treatmentcomponents 360 a, 360 b, 360 c, and 360 d; a sludge treatment component370; and a sludge transfer conduit 366. Likewise, the desalinationsystem of the vessel 315 includes a SW intake 380, a desalinationcomponent 376, a desalinated water discharge port 377; and a concentrateconduit 379. Both the WW treatment system and the desalination systemare in fluid communication with a concentrate-treated WW mixing systemthat includes a mixing tank 375 and a discharge port 390.

In addition to WW treatment and desalination, the vessel 315 furtherincludes a power producing means 322 shown in FIG. 4 as an electricalgenerator disposed on the deck of the vessel 315. The power generationsystem further includes a combustible gas conduit 324 connecting the WWtreatment component 360 d with the power producing means 322 such thatcombustible gases (e.g., methane) generated in the WW treatment processcan be used as fuel by the power producing means 322. The power producedby the means 322 can be used to operate one or more functions of thevessel 315 such as propulsion devices, control systems, desalinationcomponents, and WW treatment components. This power might also betransferred to a land-based site, such as an electricity distributioncenter for use or distribution. The transfer of energy can beaccomplished by any suitable means known in the art for transferringenergy from a vessel to a land-based site. In the embodiment shown inFIG. 4, electrical power generated onboard the vessel 315 is transferredto one or more of the WW treatment components 360 a-360 d via anelectrically conductive cable 326 a, to the desalination system 376 viaan electrically conductive cable 326 c, and to an electricity transfermeans 328 (e.g., an electrically conductive cable) via electricallyconductive cable 326 b. Through the electricity transfer means 328(e.g., electrically conductive cable), the energy can be transferred toa land-based site.

Example 5

Referring now to FIG. 5, a system for treating WW 410 includes threedifferent sea-going vessels (WW treatment vessel 415, desalinationvessel 416, and power generation vessel 417) in fluid and/or electricalcommunication with one another and positioned on a body of SW 20 viaconnecting means 491 and 492; a WW intake pipeline 440 fluidlyconnecting the vessel 415 with a land-based sewer facility 432; adesalinated water pipeline 478 fluidly connecting the vessel 416 with aland-based desalinated water distribution facility 493; and anelectricity transfer means 428 (e.g., a cable) electrically connectingthe vessel 417 with a land-based electricity distribution center 494.

In operation, WW treatment is performed on vessel 415, desalination ofSW is performed on vessel 416, and power generation is performed onvessel 417. Vessel 415 receives WW to be treated from the land-basedsewage collection facility 432 via the treated WW pipeline 440. Sludgeproduced in the WW process is returned to land or discharged into thebody of SW 20 (e.g., after dilution). Vessel 416 desalinates SW taken upfrom the body of SW 20. The desalinated water is transferred to theland-based desalinated water distribution facility 493 via thedesalinated water pipeline 478. The concentrate resulting from thedesalination process is transferred to vessel 415 via the connectingmeans 491, where it is mixed with treated WW to produce aconcentrate-treated WW mixture that is discharged into the body of SW20. Alternatively, treated WW generated on vessel 415 can be transferredvia apparatus connecting means 491 to vessel 416, where it can be mixedwith the concentrate prior to discharge into the body of SW 20.

The power producing vessel 417 includes a power producing means and isarranged to receive combustible gases that result from the WW treatmentprocess on vessel 415 via the apparatus connecting means 492. The energygenerated on vessel 417 can be used to power systems (e.g., propulsion,desalination systems, or WW treatment systems) on one or more of thevessels. Power generated on vessel 417 can be transferred to vessel 415and 416 by any suitable means. As an example, the apparatus connectingmeans 491 and 492 can include an electrically conductive cable fortransferring electrical power from the vessel 417 to the other vessels415 and 416. In FIG. 5, at least a portion of the electricity generatedon vessel 417 is transferred to a land-based electricity distributioncenter 494 by an electricity transfer means 428 (e.g., a seabed cabledisposed on top of or under the sea floor).

Other Embodiments

While the above specification contains many specifics, these should notbe construed as limitations on the scope of the invention, but rather asexamples of preferred embodiments thereof. Accordingly, the scope of theinvention should be determined not by the embodiments illustrated, butby the appended claims and their legal equivalents.

1. A method of treating wastewater on at least one apparatus positionedat a location on the surface of a body of seawater, the methodcomprising the steps of: intaking wastewater into the at least oneapparatus; treating the wastewater taken into the at least one apparatusto yield end products comprising treated wastewater and sludge; dilutingat least one of the end products to yield an at least one diluted endproduct; and discharging the at least one diluted end product into thebody of seawater.
 2. The method of claim 1, wherein the at least onediluted end product has a salinity level substantially equal to thesalinity level of the seawater at the area where the at least onediluted end product is discharged
 3. The method of claim 1, wherein theat least one diluted end product has a temperature substantially equalto the temperature of the seawater at the area where the at least onediluted end product is discharged.
 4. The method of claim 1, wherein thestep of diluting the at least one end product is performed on the atleast one apparatus in a mixing tank comprising a space in which the atleast one end product can be mixed with a diluent to form the at leastone diluted end product, an inlet for introducing the at least one endproduct into the space, an inlet for introducing seawater into thespace, and an outlet for discharging the at least one diluted endproduct from the space, the outlet being in fluid communication with adischarge port.
 5. The method of claim 1, wherein at least about 75million liters of wastewater are treated per day
 6. The method of claim1, further comprising transferring wastewater to be treated from aland-based site to the apparatus.
 7. The method of claim 6, furthercomprising transferring one of the end products from the apparatus toland
 8. The method of claim 7, wherein the one of the end products istreated wastewater.
 9. The method of claim 7, wherein the one of the endproducts is sludge
 10. The method of claim 1, wherein the at least oneapparatus consists of a single sea-going vessel or a platform.
 11. Themethod of claim 1, wherein the at least one apparatus comprises at leasttwo devices in fluid communication, the devices being selected from thegroup consisting of a sea-going vessel and a platform.
 12. The method ofclaim 1, wherein the wastewater taken into the at least one apparatus israw sewage from which undissolved solids or liquids have been removed.13. The method of claim 1, wherein the at least one apparatus comprisesa nuisance reduction system for reducing a nuisance selected from thegroup consisting of sound and odor.
 14. The method of claim 1, whereinthe step of treating the wastewater yields a combustible gas and themethod further comprises converting the gas into electricity.
 15. Themethod of claim 14, wherein the electricity is used to power anelectricity-using device on the at least one apparatus
 16. The method ofclaim 14, wherein the electricity is used to power an electricity-usingdevice not on the at least one apparatus.
 17. The method of claim 16,wherein the electricity-using device is located on land
 18. The methodof claim 1, wherein the step of diluting at least one of the endproducts comprises mixing the at least one of the end products withseawater.
 19. The method of claim 1, further comprising the steps of:intaking seawater into the at least one apparatus; and desalinating theseawater on the at least one apparatus to yield desalinated water and aconcentrate; wherein the step of diluting at least one of the endproducts comprises mixing the at least one of the end products with theconcentrate such that the at least one diluted end product comprises atreated wastewater-concentrate mixture.
 20. The method of claim 19,wherein the at least one diluted end product has a salinity levelsubstantially equal to the salinity level of the seawater at the areawhere it is discharged.
 21. The method of claim 19, wherein the at leastone diluted end product has a temperature substantially equal to thetemperature of the seawater at the area where it is discharged.
 22. Themethod of claim 19, wherein the at least one apparatus comprises atleast a first device selected from the group consisting of a sea-goingvessel and a platform and a second device selected from the groupconsisting of a sea-going vessel and a platform, wherein the first andsecond devices are in fluid communication; and wherein the step oftreating the wastewater taken into the at least one apparatus to yieldend products comprising treated wastewater and sludge is performed onthe first device and the step of desalinating the seawater is performedon the second device.
 23. A method of treating wastewater on at leastone apparatus positioned at a location on the surface of a body ofseawater, the method comprising the steps of: intaking wastewater intothe at least one apparatus; treating the wastewater taken into the atleast one apparatus to yield end products comprising treated wastewaterand sludge, intaking seawater from the body of seawater at a first depthinto the at least one apparatus; diluting at least one of the endproducts with the seawater to yield an at least one diluted end product;and discharging the at least one diluted end product into the body ofseawater from a site not at the first depth.
 24. The method of claim 23,wherein the body of seawater comprises a layer of phytoplankton and thefirst depth is below the layer of phytoplankton.
 25. The method of claim23, wherein the body of seawater comprises a thermocline and the atleast one diluted end product is discharged at a site in or below thethermocline and the first depth is above the thermocline.
 26. The methodof claim 23, wherein the body of seawater comprises a thermocline andthe at least one diluted end product is discharged at a site above thethermocline and the first depth is in or below the thermocline.